Facile Preparation of Durable Multicolor Superhydrophobic Coatings for Concrete Protection

Abstract

Concrete is extensively used in construction, roadways, and other engineering fields. However, its hydrophilic and porous structure renders it susceptible to oxidative corrosion, sand erosion, and acid rain when exposed to outdoor environments. Therefore, developing superhydrophobic coatings with superior waterproofing properties is a critical strategy to protect concrete. Nevertheless, existing superhydrophobic concrete coatings suffer from issues, such as poor durability, complex application processes, restricted color options, and difficulties in large-scale production. Herein, a spraying method is developed that utilizes nano-SiO₂, epoxy resin, cetyltriethoxysilane, and iron oxide dyes to produce a robust, corrosion-resistant, and multicolored superhydrophobic concrete coating with red, yellow, blue, and green colors. The produced coatings exhibit a water contact angle (CA) of 156° ± 1° and a sliding angle (SA) of 5° ± 1°. The hydrophobicity of the coatings arises from the synergistic effects of cetyltriethoxysilane, which provides low surface energy, and SiO₂, which creates micro and nanoscale roughness on the coating surface. Meanwhile, the coating's robustness stems from the adhesive properties of epoxy resin and hydrogen-bonding interactions between SiO₂ and the concrete substrate. Thus, the developed superhydrophobic coating shows significant potential for extending the lifespan of concrete building facades, enhancing decorative and waterproofing features, and ensuring surface cleanliness.